Flac - Nov 2006 - Flac files differ?

Hi.

Is it normal that if I encode the same file with the same options,..
that the encoded files have same size but are different?

Best wishes,
Chris.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: calestyo.vcf
Type: text/x-vcard
Size: 155 bytes
Desc: not available
Url :
http://lists.xiph.org/pipermail/flac/attachments/20061103/2a11f35a/calestyo.vcf

On 11/3/06, Christoph Anton Mitterer <calestyo@scientia.net>
wrote:
> Hi.
>
> Is it normal that if I encode the same file with the same options,..
> that the encoded files have same size but are different?
>
> Best wishes,
> Chris.
Hi.

AFAIK, compressed output is generally determined solely by input.
(Exception: Ogg Vorbis files have random serial numbers which can
result in different compressed output with identical input material,
but if you force all encodes to have the same serial number, then
identical input results in identical output.)

I don't think FLAC encoding uses serial numbers, so if you're using
one encoder to encode identical files, you should get identical
results.

Cheers,
Kyungjoon Lee

Kyungjoon Lee wrote:
> Hi.
>
> AFAIK, compressed output is generally determined solely by input.
> (Exception: Ogg Vorbis files have random serial numbers which can
> result in different compressed output with identical input material,
> but if you force all encodes to have the same serial number, then
> identical input results in identical output.)
>   
I've thought that, too. =)

> I don't think FLAC encoding uses serial numbers, so if you're using
> one encoder to encode identical files, you should get identical
> results.
Yes that was the problem,.. the help of flac (flac -H) in version 1.1.2
says:
      --serial-number          Serial number to use for the FLAC
stream.  When
                               encoding and no serial number is given, flac
                               uses '0'.  When decoding and no number is
                               given, flac uses the serial number of the
first
                               page.

Which is obviously wrong,.. as the encoder seems to use random numbers.
If I specify the number to a fixed value (the starting number) the files
are equal.

I'll file a bug report.

Thanks,
Chris.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: calestyo.vcf
Type: text/x-vcard
Size: 155 bytes
Desc: not available
Url :
http://lists.xiph.org/pipermail/flac/attachments/20061105/f276b93b/calestyo.vcf